This study will examine and further elucidate the epidemiology of peptic ulcer disease and dyspepsia. Three samples will be drawn from patients from the VA Wadsworth clinics: 100 men with duodenal ulcer; 100 men with dyspepsia negative to all tests; and 100 control men without any history of ulcer disease, matched to the duodenal ulcer cases on the basis of age and race. Risk profiles will be developed for each of these groups. The dyspeptics negative to all tests will be compared with the duodenal ulcer cases and the controls to determine if this group, or a subset, can be considered as representing a pre-ulcer population. Comparisons of the risk profiles of the three groups will be made--the risk profiles will be based on demographic characteristics, genetic markers, psychosocial risk factors, medical history, and biochemical variables. An attempt will be made to develop a classification scheme based on risk profiles and to determine if there is an identifiable subset of patients with dyspepsia negative to all tests who could be regarded as having a mild and/or pre-ulcer condition. In addition, conducted by means of a subcontract to Los Angeles County Harbor General Hospital (under Dr. Jerome I. Rotter) an investigation will be made of the interaction of the genetic and environmental factors in peptic ulcer.